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Bird Communities Along the Altitudinal Gradient on Mt. Cameroon: Perspectives from Mist Nets
Petruf, Miroslav ; Sedláček, Ondřej (advisor) ; Lučan, Radek (referee)
in English Mt. Cameroon is a hotspot of diversity and endemism in Africa. Recent research of avian bird communities along the elevational gradient on Mt. Cameroon based on point counts has shown low-elevation plateau of species richness. At the same time, range-restricted montane populations of birds on Mt. Cameroon are unusually abundant if compared to lowland species. I analysed data on community composition, species richness and abundance of birds using an alternative quantitative method - 200 m of understory mist nets erected for three consecutive days across seven elevational plots along the forested gradient of the Mt. Cameroon. First, I looked at the technical limits of this method and confirmed the general opinion that they are better at detecting small birds below 33 g, and that they mostly detected fewer individuals after the first day and always detected fewer new species after the first day of mist-netting. Mist nets detected high proportions of ground-feeding and understory birds and low proportions of birds foraging in higher strata in the lowland forest, which has a scarce understory and a dense canopy. Mist nets recorded similar proportions of birds foraging in all forest strata in the vastly open mid-elevation forest, which has a dense herbaceous understory. They detected higher...
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Niche Partitioning in Tropical Birds
Petruf, Miroslav ; Sedláček, Ondřej (advisor) ; Exnerová, Alice (referee)
in English Niche partitioning is a process that allows species to coexist by minimizing competition. Niches get narrow with growing habitat heterogeneity, which is evident in tightly packed tropical communities. Closely related species exhibit a high niche overlap, which intensifies competition for resources in their sympatry. Such birds avoid competitive exclusion by foraging using different methods or in different strata. Character displacement makes sympatric species diverge in foraging niches as well as in morphology, allowing specialized species to access private resources. Tropical birds in seasonal environments tend to occupy different niches in the wet and in the dry season, based on the availability of resources in their preferred habitats. Resource subdivision in sympatric members of an ecological guild usually depends on body-size- determined dominance. Territoriality may depend on the costs and benefits of defending resources, which may change seasonally. Dominance statuses vary within populations of the same species, too, promoting intra-specific niche partitioning. Within-species differences in foraging can also be the result of sexual dimorphism or differences in reproductive roles. Moreover, intra-specific differences in foraging may also explain the partial migration of some...
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